Know how much water you have. From anywhere.
On your phone or in a browser, you see the fill level as a percentage and the water level in meters, accurate to within centimeters. No need to lift the lid.
You do not have to worry about your water. Hastr watches it for you.
Hastr Water Level measures the level in a well, tank or cesspit from above, with no lid to lift. You find out in time when the water is running low or the cesspit is filling up, wherever you are.
- 0.03–20 mone model for a tank and a deep well
- No cable to the tankover a year without charging, then it charges like a phone
- No annual feethe app, alerts and updates are included
- Installed in 15 minutesyou can do it yourself
Your tank can be anywhere on your property
Only a battery-powered device goes into the tank, mounted at the top, above the water. The device sends its readings by long-range radio to the Hub, a small box that comes in the package, and you plug it into a socket at home by your router. So no cable runs to the tank, and your Wi-Fi does not need to reach it.
- A tank buried under the lawn, under a concrete lid
- A well in the corner of the garden
- A cesspit behind the shed
What the water level sensor watches over
Rainwater tank
You know how much water you have for flushing without opening the tank. After rain, the chart in the app shows how much the level rose.
Well
You notice in time that the water is going down. The chart in the app for the last 7 or 30 days shows whether the level recovers after pumping. When it drops below a limit you set, an alert arrives.
Irrigation tank
You know the irrigation water is running low before the lawn does. The irrigation controller will not report an empty tank by itself. When the level drops below your limit, the water level sensor sends you an alert.
- Coming soon
Cesspits and holding tanks
You book the emptying in time. The water level sensor alerts you when the cesspit is filling up, so you do not have to go and check it.
What you get
Hastr alerts you when the level drops below your limit
In the app, you set the limit as a height above the bottom of the tank, in meters. When the water drops below it, you get a push notification and an email. For a cesspit it works the other way round: the alert comes when the level rises above the limit. Once the level is back, you get a message that it is fine again.
One model for a tank and a deep well
The device reads the water level anywhere from 3 cm to 20 m below it. You do not need to know the depth of your well in advance or pick a range when you buy.
You do not have to think about the device in the tank
The device measures from above and does not touch the water, so nothing builds up on it. The battery lasts more than a year, depending on how often the device measures. When the battery drops to 20%, we send an alert and you charge the device over USB-C. New features reach the device on their own, remotely.
Pay once
You pay once for the water level sensor. The app, alerts, measurement history and updates are included, with no annual fee.
One Hub watches over several tanks
For another tank, you buy only a device. You already have the Hub, the box at home by your router. For a property out of its range, you add another Hub and switch between them in the app. Send your family or a service company an invitation by email and they see the same tanks.
Installation
Install it yourself in 15 minutes
You mount the device at the highest point of the tank, above the maximum level, facing down at the water. You plug the Hub into a socket at home and connect it to your Wi-Fi. Finally, in the app, you enter the distance from the bottom to the device, the maximum level and the current level.
Comparison
How the water level sensors sold in Czechia differ
We compare types of water level sensor as you find them in shops, not specific products. The data come from the public websites of manufacturers and sellers, checked in October 2026.
| Feature |  Hastr Water Level | Probe with Wi-Fi | Ultrasonic with Wi-Fi | Probe with a SIM card | Mechanical float |
|---|---|---|---|---|---|
| One model for depths of 0.03–20 m | yes | partly you pick the range when you buy, and a deeper tank costs extra | no up to 2.5–7.5 m, depending on the model | partly you pick the range when you buy, and a deeper tank costs extra | no a scale depending on the model, for example 0–2 m |
| Works where Wi-Fi does not reach | yes by long-range radio to the Hub, even through a concrete lid | no Wi-Fi has to reach the control unit | no Wi-Fi has to reach the tank | yes over the mobile network | partly you see the reading only at the tank |
| Nothing in the water | yes | no the probe is submerged | yes | no the probe is submerged | no the float sits in the water |
| No power needed at the tank | yes battery-powered device | partly most need power at the tank | partly most need power at the tank | partly most need power at the tank | yes |
| A dedicated app for iOS and Android | yes in Czech and English | partly only some, the rest a web page | partly only some, the rest a web page | partly only some, the rest a web page | no |
| Push notifications to your phone | yes push and email | partly only some, the rest email, SMS or social media | partly only some, the rest SMS and email | no email or SMS | no |
| Several tanks and properties in one app | yes | partly only some | partly only some | no | no |
| Sharing with your family | yes | partly only some | partly only some | no | no |
| Full measurement history with no time limit | yes | no some keep only 3 months | no | no 3 months, or as long as you pay | no |
| Remote updates included | yes Hub and device | partly only some | no | no | no |
| No annual fee and no SIM card | yes | yes | yes | no a data SIM card with a plan, or a paid data package | yes |
What you see in the app
- Current level in meters and fill level as a percentage
- Level chart for 24 hours, 7 or 30 days
- Battery and signal status for each device
- Several tanks and properties in one overview
- Access for other people, just send them an invitation by email
For iOS and Android, and in a browser on your computer. In Czech and English, in light and dark mode.
Get the app
Features and specifications
Measurement
Radar measures from above
The device does not touch the water, so nothing builds up on it.
Range 0.03–20 m
One model for a shallow tank and a deep well.
Accurate to within centimeters
Measurement interval of 5, 15, 30 or 60 min
Or one you set yourself. Measuring more often shortens battery life.
Calibration to your water level
During setup you enter the current level and the device calibrates itself to it.
Tank types
Rainwater tank, cesspit, well and drinking water tank.
Alerts
Low level alarm
For a cesspit, a high level alarm. You set the limit in meters.
A message when the level is fine again
Turn the alarm off and the limit stays saved
Push notification and email
Low battery alert
Sent when the battery drops to 20%.
Alert when the device or the Hub stops responding
The Hub after an hour, the device after 24 hours. We let you know when it is back online, too.
App
iOS, Android and web
Level in meters, fill level as a percentage
Chart for 24 hours, 7 and 30 days
Battery, signal and last reading
Several tanks and properties
Each property has its own Hub, and you switch between them in the app.
Sharing with other people
You send an invitation by email to your family or a service company. The invited person sees the readings and can change settings.
Czech, English and dark mode
Sign-in without a password
A code or link arrives by email.
Report a problem from the app
Device and Hub
Battery lasts more than a year
It depends on how often the device measures.
Charging over USB-C
While charging, the indicator light shows the battery status.
No power needed at the tank
Hub on 2.4 GHz Wi-Fi
It sits at home by the router, plugged into a socket.
Remote updates
The device and the Hub get new features on their own, with nothing for you to install.
Connectivity and price
Long-range radio
In our test the signal got through even from a tank under a concrete lid.
You pay once
App, alerts and updates with no annual fee.
Technical specifications
- Measurement method
- 60 GHz radar, contactless from above
- Hub power supply
- 230 V wall adapter, USB-C connector
- Device charging
- USB-C, 5 V
- Default measurement interval
- 5 min
Coming soon
Hub on the 5G mobile network
For places without Wi-Fi.
Smart home integration
Home Assistant and Loxone.
Frequently asked questions
Where can I buy the water level sensor?
We sell through partners. Leave us your contact details and we will put you in touch with a partner who supplies it.
I'm interestedDo I pay anything yearly?
No. The basic app, alerts, measurement history and updates are included in the price of the water level sensor.
How far does the signal reach?
The device sends data to the Hub by long-range radio, not over Wi-Fi. In our test on a real property, not a single message was lost from a device under a concrete lid inside the tank or from a device in a shed behind a stone wall. We do not quote a distance in meters, because what stands between the device and the Hub matters more than meters. If the connection is weak, move the Hub closer to the tank, for example to a room on that side of the house that your Wi-Fi still reaches.
What if the internet goes down?
The Hub needs the internet to get readings and alerts to the app. During an outage, no new data arrives. If the Hub is silent for an hour, we send you a message, and once it reconnects, readings arrive again.
Do I need power at the tank?
No. The device runs on a battery, and only the Hub plugs into a socket, at home by your Wi-Fi router. You need no electrician and no rewiring.
How long does the battery last?
The battery lasts more than a year, depending on how often you set it to measure. The more often it measures, the shorter it lasts. When the battery drops to 20%, we send you an alert and you charge the device over USB-C.
Do I have to measure the tank?
Only once, during setup. You enter the distance from the bottom to the device, the maximum level and the current level. The device calibrates itself to the current level.
Does the water level sensor work in a cesspit?
Yes. When you choose cesspit as the tank type in the app, the alarm watches for a high level instead of a low one. You find out in time that it is time to book emptying.
Can I monitor several tanks?
Yes. You mount one device in each tank and connect them all to one Hub. You see them side by side in the app. A property out of the Hub's range needs its own Hub, and you switch between Hubs in the app.
Can others in my household see the level?
Yes. Send them an invitation by email. Each person signs in on their own phone and sees the same tanks.
Where to buy
Hastr is sold by our partners
Tell us you are interested. We will put you in touch with a partner who will deliver the water level sensor and tell you the final price.
Contact
Have questions? Get in touch.
Partnership, technical questions, or just an idea to discuss.
Write to us, we're happy to help.
Send us an email
info@resonect.czCall us
+420 602 600 714Other contact details
Resonect Technology s.r.o.
IČO: 19754213
Opletalova 929/22, 110 00 Praha 1
Guides & Installation
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